I‘d hazard a guess that *where* you are—how good the cellular and wifi signal are, etc—has a big influence as well.
And of course display brightness.
And if you use your 120Hz screen constantly, e.g. by continually scrolling through web pages or social media, the gpu has to work somewhat hard, while on static screen content or low(er) frame rate videos, the graphics subsystem can reduce the display refresh rate, saving energy. Plus a white text page makes the OLED use more power than a dark(ish) video.
And of course display brightness.
And if you use your 120Hz screen constantly, e.g. by continually scrolling through web pages or social media, the gpu has to work somewhat hard, while on static screen content or low(er) frame rate videos, the graphics subsystem can reduce the display refresh rate, saving energy. Plus a white text page makes the OLED use more power than a dark(ish) video.